UNITED STATES ENVIRONMENTAL PROTECTION AGENCY GUIDANCE FROM HOTLINE COMPENDIUM WSGH32 SUBJECT: Repeat Monitoring Requirements for the Total Coliform Rule SOURCE: Clive Davies On June 29, 1989, National Primary Drinking Water Regulations for Total Coliforms were promulgated (54 FR 27544). Under the final rule, systems are required to collect repeat samples for each total coliform-positive routine sample; three for systems collecting more than one routine sample per month, four for systems taking one routine sample per month (Section 141.24(b)). Section 141.24(b)(4) states that if one or more repeat samples is total coliform-positive, systems must collect additional sets of repeat samples until total coliforms are not detected in a set of repeat samples, or the system determines that the MCL for total coliforms has been exceeded and notifies the State. In some cases, a system may have determined that an MCL has been exceeded prior to taking a second set of repeat samples. For example, if a system collects six routine samples per month, one of which is total coliform-positive, and the system then takes a repeat set of samples resulting in another total coliform-positive sample, the system is out of compliance. In this case, would a system determined to be out of compliance after taking only one set of repeat samples be required to take the additional set of samples as stated in Section 141.24(b)(4)? Response: Under the provisions of Section 141.21(b)(4), no further repeat monitoring for total coliforms is required for the system in the above case. However, all positive samples must be analyzed for fecal coliform or E. Coli, as required by 141.21(e)(l), whether or not the MCL had been exceeded. Failure to conduct this monitoring is a Monitoring Violation. If any total coliform-positive sample is found to be fecal coliform-positive or E. Coli - positive, the system must notify the State. The State may then require additional repeat monitoring even if the MCL has been exceeded. The following sampling/analysis must always be done, even if the MCL has been exceeded. All routine and repeat total coliform-positive samples must be speciated for fecal coliforms or E. Coli. Also, all repeat samples must be taken for all routine total coliform-positive samples. This additional monitoring after the monthly MCL has been violated allows the State to determine if the acute MCL has also been violated. ------- |